It is known to locate a marker in the ground to delineate a path, to indicate distance to an object, or to convey information (such as a historical plaque). At golf courses for instance, markers are typically used to indicate the distance from the marker to the centre of the green.
One type of marker often used at golf courses is a coloured stake, or another identifiable indicator, protruding from the ground a predetermined distance (usually 150 yards) from the centre of the green. The golfer estimates by eye, or paces off, the distance between his ball and the marker to determine how far his ball is from the centre of the green. The golfer is then better able to decide on the appropriate club to use to hit the ball on to the green.
A problem with this type of marker is that it protrudes from the ground and thus acts as an unnatural obstruction on the golf course. As a result, only one or two markers are used on each hole, and usually these are located at the sides of the fairway. Because only one or two markers are provided, it is often difficult for the golfer to quickly and accurately estimate the distance of his shot. It is especially difficult if the golfer's ball is on the opposite side of the fairway from the marker, and thus at a different angle toward the green. Speed of play is effected by the golfer's indecision. The time required for the golfer to estimate the distance by eye, or to pace off the distance to the marker tends to frustrate other golfers, and can have an economic effect upon the golf course (by reducing the rate of golf rounds per hour).
Another type of marker used at golf courses, often in conjunction with the first type of marker, is a numerical marking that is affixed to the top of sprinkler heads that may be submerged throughout the fairway. Unfortunately, the sprinkler heads are not located at consistent positions about the fairway and are generally too far apart to be easily located by the golfer. Also, the small size of the sprinkler heads only accepts small size yardage markings, which tend to be difficult to read. For these reasons, time is again wasted as golfers wander about trying to locate the sprinkler heads to estimate distances. Also, in many climates, courses do not require a sprinkler system.
Another type of marker used at golf courses is a cement slab located generally flush with the ground along the centre line of the fairway. Such slabs may be colour-coded and located at predetermined distances along the fairway. For instance, a red slab may be located at 100 yards, a white slab at 150 yards, and a blue slab at 200 yards. A problem with the concrete slabs is that they tend to cause unnatural bounces of a golf ball and thus act as an unnatural obstruction on the course. In addition, the slabs can cause damage to other pieces of golf course equipment, such as aerating machines. For these reasons only a few slabs would be used for each hole, which leads to the same speed and accuracy problems as were associated with the first type of marker.
Yet another type of marker is described in U.K. patent application 2,202,155 (Solheim) published in 1988. This application describes a marker that is substantially submerged in the ground at predetermined distances on opposite sides of an imaginary centre line of the fairway. The markers are anchored to the ground with cement with the top of the markers extending slightly above ground level.
There are a number of problems with the Solheim marker. For instance, the Solheim marker is not easily removable from the fairway. This is a problem since it does not permit the fairways to be periodically aerated without damaging the aerating machines or the markers. Furthermore, grass tends to grow over markers that are close the ground. When the markers have a relatively small surface area, such as the Solheim markers, it is necessary to trim the grass to avoid the marker from being obliterated. It would be a time consuming task to trim the grass around the numerous permanently anchored markers described in the Solheim application. Also, the upper surface of the Solheim marker is convex in profile and protrudes slightly above ground level to expose a side edge. A golf ball striking the convex surface or the side edge would be deflected unnaturally compared to a golf ball striking the grassy ground. This is, of course, undesirable since the marker should be as unobtrusive as possible. The risk of a golf ball striking the marker surface is multiplied as more markers are located about the fairway. Furthermore, the marking system described in Solheim utilizes only a pair of markers at each distance. This provides little assistance on wider fairways, where the golf ball may be located some distance away from the markers.
There is a need for a ground marker that is easily removable from the ground and that does not require frequent trimming of the grass that tends to grow over its surface. The ground marker should be unobtrusive when used as a distance marker at golf courses so that it will not effect the flight of a golf ball. Finally, the ground marker should be inexpensive to manufacture and easy to install or remove.
An additional problem faced by golf courses is the cost involved in operating the course. The cost of obtaining and servicing equipment, such as markers, can be prohibitive. To recover a portion of these costs, some golf courses have rented advertising space at locations around the golf course. Commercial advertisements have appeared on signboards located at the tees, and in the golf cups located in the green (see U.S. Pat. No. 5,249,384 to Dark, Jr.). While these methods of advertising provide an additional source of revenue, it is desirable that further methods of obtaining advertising revenue be developed. Preferably, these methods would be relatively unobtrusive so as not to deter from the appearance of the golf course and the play of the game.